• The supporting, sustentacular or Sertoli cells were
discovered by Italian histologist, Enrico Sertoli. Sertoli
cells are large, elongated and pyramidal cells which have
bases adhering to basal lamina (basement membrane) and
apices projecting into the lumen of the seminiferous tubules
providing attaching sites to spermatocytes and spermatids.
• Sertoli cells secrete androgen binding protein (aBP) that
concentrates testosterone in the seminiferous tubules.
Sertoli cells also secrete another protein called inhibin
which suppresses FSh synthesis. They secrete spermatogenic
substances for nourishing and differentiation of cells
undergoing spermatogenesis, therefore, Sertoli cells are also
called nurse cells.
• Leydig’s cells are interstitial cells present in the connective
tissue around the seminiferous tubules. These cells were
discovered by German anatomist Franz Leydig.
• Leydig’s cells are endocrine in nature. Under the influence
of luteinising hormone (Lh) or interstitial cell stimulating
hormone (IcSh), Leydig’s cells produce androgens, e.g.,
testosterone. The latter not only produce and maintain male
characteristics but also stimulate germinal epithelium to
undergo spermatogenesis.
Blood-testis barrier
Sertoli cells maintain blood-testis barrier which prevents many
cells from entering or leaving seminiferous tubules. It also
prevents sperms from diffusing into the blood. This is because
sperms are immunogenic and can result in development of
antibodies specific to them. This barrier develops at the time
of puberty, just before beginning of spermatogenesis, and
provides a protected environment for sperm development and
maturation.
• In some persons testes fail to descend in scrotum. The
condition is called cryptorchidism. It results in sterility.
• Testes perform two functions : (a) production of sperms and
(b) secretion of male sex hormones.
male accessory ducts
• Rete testis, vasa efferentia, epididymides and vasa
deferentia, (or vas deferens) are called the male
accessory ducts. These ducts store and
transport the sperms from the testis to
the outside through urethra.
• The seminiferous tubules are
closed at one end but on
the other side they join to a
network the rete testis from
where fine ciliated ductules, the
vasa efferentia arise. cilia help in
conducting sperms.
• Epididymis is a mass of long narrow closely coiled tubule
which lies along the inner side of each testis.
• at the anterior end of the testis epididymis is called caput
epididymis, in which the vasa efferentia opens. The middle
part of the epididymis is known as corpus epididymis.
The posterior end of the epididymis is called as cauda
epididymis.
• In the head of the epididymis, the sperms undergo
physiological maturation, acquiring increased motility and
fertilising capacity. In the tail of the epididymis sperms are
stored before entering the vas deferens.
• Epididymis is lined by pseudostratified epithelium that
secretes nutrients required for maturation and nourishment
of spermatozoa. Non-ejaculated sperms are reabsorbed in
the vasa deferens.
• The term testicle is used for both testis and epididymis.
• The vas deferens is a continuation of the cauda epididymis
which leaves the scrotal sac and enters the abdominal cavity
through the inguinal canal.
• The vas deferens loops over the urinary bladder where
it is joined by duct from the seminal vesicle to form the
ejaculatory duct. Vasa deferentia carry sperms.
Table : Differences between vasa efferentia and
vasa deferentia
Vasa efferentia Vasa deferentia
(i) They arise from the rete
testis.They arise from the cauda
epididymis.(ii) They vary from 15 to 20
in number.They are only 2 in
number.(iii) Vasa efferentia are fine. Vasa deferentia are thick.(iv) Their lining bears many
ciliated cells.Their lining has many
stereocilia.(v) They carry spermatozoa
from the testis to the
epididymis.They carry spermatozoa
from cauda epididymis to
the ejaculatory duct.ejaculatory ducts
• They are formed by the union of ducts
from vas deferens and duct of seminal
vesicle.
• In ejaculatory ducts, the sperms
mix up with secretion of seminal
vesicles. The walls of ejaculatory ducts
are muscular to quickly conduct the
ejaculate through urinogenital duct.